This invention concerns a process for preparing a glass-like plastic mass from a mixture of sweetening agents.
The preparation of sugar substances for confectionery purposes based on an extrusion process is known. DE 24 61 543 C2 describes such a process in which liquid glucose and crystal sugar are fed into a double-screw extruder, this mixture is kneaded at elevated temperature and pressure, the pressure is reduced and the mixture is compressed. A decrystallised melted sugar substance is obtained which can be used afterwards for preparing hard caramel sweets, for example.
From U.S. Pat. No. 5,472,733 a process is known for preparing a glass-like plastic mass, in which process a sweetener is fed into a double-screw extruder, the sweetener is melted and fed through adjustable baffles. The patent describes how a glass-like plastic mass can be obtained by the setting of particular pressure ratios controllable by means of a pressure relief valve and particular temperature equalisation.
The described process has the disadvantage that the glass-like plastic mass obtained in the output from the extruder has comparatively high temperatures and that is why it has to be cooled on cooling conveyors of appropriate length. This requires major expenditure on equipment and relatively large building space for the cooling conveyors as well as prolonged cooling times. In addition, the incorporation of flavourings and active ingredients has to carried out at high temperatures, which in many cases has undesirable effects on the stability of the incorporated tastes and active ingredients.
Thus the underlying technical problem of the invention is in providing a process for preparing a glass-like plastic mass, preferably sugar-free, suitable for confectionery purposes, which overcomes the afore-mentioned disadvantages, in particular leading, to a product which can be easily processed further.
The underlying technical problem of this invention is solved by providing a process for preparing a glass-like plastic mass, preferably sugar-free, from a mixture of sweetening agents, in which the sweetening mixture is fed into the charging zone of an extruder, especially a double-screw extruder, then into a melting zone at elevated temperature, following this into a vacuum zone at reduced pressure and increased temperature, and following this is extruded into a cooling zone at reduced temperature and a glass-like plastic mass is obtained. The process according to the invention thus results in a glass-like plastic mass being obtained, which has a reduced temperature compared with the temperature prevailing in the melting zone and therefore can be cooled considerably faster and on shorter cooling conveyors. Furthermore, it is possible to incorporate flavourings and/or active ingredients, in particular pharmaceutically-active ingredients, at lower temperatures in the cooling zone.
Obviously it is also possible to feed the flavourings and/or active ingredients into the sweetener mixture or sweetening agent before feeding into the charging zone, if the flavourings or active ingredients are temperature-stable.
The use of the so-called in-line mixers, which usually are used for this purpose in the traditional extrusion process, can be omitted. In addition, the process according to the invention is advantageous in that the expenditure on equipment, particularly the design of the screw extruder, is comparatively simple. A screw extruder which can be used according to the invention requires no adjustable baffles or screw elements, which regulate the stream of the extrusion mass, and is commercially available from the Togum Company.
In the context of this invention, a sweetening agent is understood to mean a substance with properties producing a sweet sensation, which is found, depending on specific implementation, in foodstuffs, stimulants, pharmaceuticals or similar material and which can be used as a carrier or additive for pharmaceutically-active additives, flavourings, tastes, fragrances or colourings. In a particularly advantageous way, the sweetening agent mixture used for the process according to the invention contains 100% of the sweetening agent cited below or a mixture of at least two of these sweetening agents. However, provision can be made for the sweetening agent mixture to contain only 1-99%, preferably 50-95%, of the sweetener agent cited below and in addition to have flavourings, active ingredients, minerals, salts, carriers and fillers, for example polymers.
The sweetening agent can be inulin, invert sugar, a 1:1 mixture of 6-O-xcex1-D-glucopyranosyl-D-sorbitol (1,6-GPS) and 1-O-xcex1-D-glucopyranosyl-D-mannitol (1,1-GPM) known from DE 25 20 173, a sweetening agent described in EP 0 625 578 B1 consisting of 1,6-GPS, 1,1-GPM, 1-O-xcex1-D-glucopyranosyl-D-sorbitol (1,1-GPS), mannitol, sorbitol and oligosaccharides, polydextrose, hydrogenated and non-hydrogenated starch hydrolysate, a sugar alcohol a monosaccharide or disaccharide as well as a polysaccharide. Xylose, ribulose, glucose, mannose, fructose. isomaltose, isomaltulose, galactose, saccharose, maltose and the like can be considered as a monosaccharide or disaccharide. Sorbitol, xylitol mannitol galactitol, maltitol, 1,6-GPS, 1,1-GPS, 1,1-GPM and the like can be considered as a sugar alcohol.
In the context of this invention, a charging zone of an extruder is understood to mean the area of the extruder in which the sweetening agent mixture to be extruded is loaded. The melting zone is understood to mean the area of the extruder in which the melting and decrystallisation of the inserted sweetening agent mixture takes place at elevated temperature. The vacuum zone is understood to mean the area of the extruder in which extrusion takes place under reduced pressure. The cooling zone is understood to mean the area of the extruder in which the extrusion mass heated during the melting process is gradually cooled.
The process according to the invention leads to a cooled glass-like plastic mass which exists advantageously in a form capable of stamping.
In a particularly preferred form of implementation of the invention, a temperature of 130xc2x0 C. to 210xc2x0 C., preferably 170xc2x0 C. to 210xc2x0 C., exists in the melting zone of the extruder. In a particular, advantageous manner, provision is made for the melting zone to be divided into several segments which are at different temperatures. According to the invention, preference is given to providing four segments in the melting zone, in which the prevailing temperature m the first segment is 177xc2x0 C., in the second segment 205xc2x0 C., in the third segment 188xc2x0 C. and in the fourth segment 191xc2x0 C.
In another particularly preferred form of implementation, provision is made for a temperature of 120xc2x0 C. to 160xc2x0 C., in particular 133xc2x0 C., to be used in the vacuum zone.
The invention preferentially provides for a pressure of 0.70 to 0.98 bar, in particular 0.78 bar, to be used in the vacuum zone.
According to another design of this invention, provision is made for a temperature of 60xc2x0 C. to 130xc2x0 C., preferably 80xc2x0 C. to 120xc2x0 C., to be used in the cooling zone. The invention particularly provides for the cooling zone to be divided into several segments which are at different temperatures. According to the invention, three segments are preferred, in which in the first segment a temperature of 120xc2x0 C. is to be used, in the second segment a temperature of 120xc2x0 C., and in the third segment a temperature of 80xc2x0 C.
The temperature data refers to the temperature in the jacket of the extruder and not in the melt The temperature in the melt is approximately 20 to 30xc2x0 C. below the jacket temperature.
The invention advantageously provides for the extruder to be designed as a double-screw extruder.
Obviously the invention can be implemented by using any extruder, provided that the latter can be correspondingly configured to the parameters according to the invention.
In an especially preferred form of implementation, the invention provides for the extruder to be sealed at its end and the extrusion mass to be drawn off towards the bottom. A particularly clear, bubble-free plastic mass is produced according to this form of implementation. Obviously it is also possible to not seal the extruder at its end but to provide it with a delivery nozzle. The extrusion mass then does not come out from the extruder towards the bottom, but in a straight extension of the longitudinal axis of the screw.
The invention also concerns a glass-like plastic mass which has been prepared in accordance with a process according to the invention, an extrudate which can be stamped and which is suitable, for example, for preparing hard caramel sweets or tablets, and products containing the plastic mass. In an advantageous manner, further cooling of the plastic mass on the cooling conveyors is not necessary during further processing before stamping of the plastic mass.
The invention also concerns a use of a glass-like plastic mass according to this invention for the preparation of tablets, in particular by pressing, the said tablets containing preferably pharmaceutically-active additives, or for the preparation of hard caramel sweets.
The invention accordingly also concerns hard caramel sweets and tablets, preferably sugar-free, which contain the plastic mass prepared by means of the process according to the invention and which can be prepared from this plastic mass by means of normal processes.